It has been found desirable for producing relatively smoothly peened surfaced workpieces and/or for shaping workpieces, such as metal sheet, plate or structural members, by shot peening to achieve such shot peening by propelling shot under low pressure air and/or gravity forces. Such peening process and apparatuses are exemplified in the U.S. Patent to Brandel etl al U.S. Pat. No. 3,705,511. However, it has been found that relying solely on gravity for propelling the shot has posed problems of suitability of the peening apparatus for a wide range of different workpiece materials because the velocity of the shot could not be varied commensurate with the kind of material to be shot peened and/or type of shot peening to be accomplished. The present invention is directed to overcoming this disadvantage.
It is, therefore, an object of this invention to provide a shot peening apparatus which is capable of providing shot peening over a wide range of different workpiece materials.
It is another object of the present invention to provide a shot peening apparatus capable of providing substantially uniform distribution of shot along a relative great flow area simply and inexpensively.
It is a further object of this invention to provide a shot peening apparatus which can achieve shaping of workpieces over a wide range of types of workpieces than heretofore known air pressure or gravity shot peening devices.
A still further object of the present invention is to provide a shot peening apparatus in which substantially uniform distribution of falling shot is achieved in an inexpensive manner.